Supra-Threshold Hearing Sensitivity Disorders and Mild Permanent Hearing Loss: Neglected Cause of Hidden Hearing Loss and Speech Defects.

Abstract

Supra-threshold disorders in the form of auditory neuropathy (AN)/auditory dys-synchrony (AD) or central auditory processing disorders (CAPD), a special type of retrocochlear hearing loss; and also children with mild permanent hearing loss (PHL), may be missed on current hearing protocols. Otoacoustic emissions (OAE) and Brain stem evoked response audiometry (BERA), are tests, when used in combination, can indirectly help diagnose the different types of hearing loss. To correlate the parental awareness and the pattern of hearing loss (HL) in children with/without auditory and/or speech problems, using both OAE and BERA as hearing tests for indirect identification of suprathreshold disorders and mild PHL. An Observational Prospective study carried out on 100 children in the age group of 0-5years, for detection of type of HL by both OAE and BERA and correlating it with parental awareness of HL and speech defects. In 72.22% of children with speech problem only and without any complaints of HL, some form of HL (confirmed HL-OAE refer/BERA fail or auditory neuropathy/auditory dys-synchrony-OAE pass/BERA fail) was diagnosed, whereas 24.07% had no detectable HL on both OAE and BERA pass, and were considered as indirect evidence of CAPD. 3.7% with OAE refer and BERA pass were considered indicative of mild PHL. AN/AD/CAPD/Mild PHL are important cause of speech delay without parental awareness of HL. OAE and BERA together can be used as an indirect evidence of their presence.